The invention relates to a drive arrangement for at least one auxiliary equipment of a vehicle. The invention also relates to a vehicle comprising such a drive arrangement.
A vehicle such as a car or a truck comprises a driveline which includes generally at least one drive engine, which can be an electric machine or an internal combustion engine, for driving driven wheels of the vehicle. In the case of parallel hybrid electric vehicles, two drive engines are provided, one internal combustion engine and one electric machine. In most cases, the internal combustion engine is connected to the driven wheels through a gearbox having at least one input shaft connected to the drive engine and one output shaft connected to the driven wheels of the vehicle.
Vehicles may need, in particular conditions, to move with their internal combustion engine in shut down state. For example, trucks can move, on moderate slopes, with their internal combustion engine shut down, in order to save fuel and avoid friction in the engine. Such case happens frequently with hybrid vehicles when they are driven with the electric machine alone.
Auxiliary equipments, like steering pumps, alternators, air compressors or other equipments are generally mechanically driven by the internal combustion engine. In order to make sure that these equipment still operate when the internal combustion engine is shut down, known solutions replace the mechanical drive of these equipments by an electrical drive. The electrical system of such vehicles must therefore be dimensioned for heavy duties due to safety issues and to the relatively low efficiency of an electrical drive.
FR-B-1 273 127 describes a drive arrangement for an auxiliary equipment in which the auxiliary equipment can be driven simultaneously by an input shaft and by an output shaft of a gearbox, thanks to a differential. This arrangement does not permit to go on delivering torque to the auxiliary equipment when the engine is shut down and when the vehicle is stopped.
It is desirable to provide a new drive arrangement for an auxiliary equipment of a vehicle, which allows to drive one or several auxiliary equipments in various operating configurations of the vehicle, particularly when the internal combustion engine is shut down with the vehicle still moving and when the vehicle is stopped with the internal combustion engine shut down, and which does not interfere with the normal operation of the drive line of the vehicle.
An aspect of the invention concerns a drive arrangement for at least one auxiliary equipment of a vehicle, comprising a gearbox having at least one input shaft connected to a drive internal combustion engine, and one output shaft connected to driven wheels of the vehicle, the drive arrangement comprising a power split device having no more than three separate input/output couplings, whereas a first coupling is connected to the input shaft, a second coupling is connected to the output shaft, and a third coupling is connected to said at least one auxiliary equipment. This drive arrangement is characterized in that it comprises an auxiliary electric machine connected to one of the couplings of the power split device, adapted to deliver torque to said at least one auxiliary equipment, and in that it comprises means to disconnect the first coupling from the input shaft of the gearbox.
Thanks to an aspect of the invention, an auxiliary equipment driven by the internal combustion engine of the vehicle can be driven when the internal combustion engine of the vehicle is shut down. The auxiliary equipment can also be operated thanks to the electric machine when specific operating conditions of the vehicle do not permit to use a mechanical only transmission. As these specific operating conditions have a relatively short duration, the electric machine used can be downsized with respect to a drive arrangement in which the drive of the auxiliary equipments is electrical only.
According to further aspects of the invention which are advantageous but not compulsory, such a drive arrangement may incorporate one or several of the followings features:                The first coupling is connected to the gearbox input shaft through an intermediate shaft of the gearbox which is permanently connected to the gearbox input shaft.        The auxiliary electric machine is connected to the first coupling.        The auxiliary electric machine is connected directly to said at least one auxiliary equipment.        The drive arrangement comprises means, arranged between the second coupling and the output shaft, to allow the transmission of a movement from the output shaft to the second coupling only in one direction.        The means to allow the transmission of movement from the output shaft to the second coupling in only one direction comprise a free wheel.        The drive arrangement comprises means to selectively block the first coupling.        The means to selectively block the first coupling comprise a free wheel connected on one side to the first coupling and on the other side to a fixed part.        The means to selectively block the first coupling from the input shaft comprise a brake system adapted to block the rotation of the first coupling.        The drive arrangement comprises means to control the means to disconnect the input shaft from the first coupling so that they disconnect the input shaft from the first coupling when the gearbox is in a gear changing phase or when the engine is shut down and the vehicle is stopped.        The drive arrangement comprises means to drive said at least one auxiliary equipment through the auxiliary electric machine when the internal combustion engine is shut down and the vehicle is stopped.        The means to control the means to disconnect and the means to drive said at least one auxiliary equipment through the auxiliary electric machine comprise at least one electronic control unit.        The means to control the means to disconnect comprise an electronic control unit, whereas the means to drive said at least one auxiliary equipment with the auxiliary electric machine comprise a power control unit, and whereas the electronic control unit and the power control unit communicate with each other.        Said at least one auxiliary equipment is a mechanically driven steering pump.        The power split device is a planetary gear.        
The invention also concerns, according to an aspect thereof, an automotive vehicle comprising the above-mentioned drive arrangement.